Device for limiting rotation

ABSTRACT

For limiting the rotational or angular movement of a drive spindle about its axis, such as in a rotary drive for the sliding roof of a motor vehicle, abutments or stops are associated with the driving spindle and with a slide movably displaceable relative to and transversely of the drive spindle, for effecting the limiting action. The drive spindle extends through a housing and the slide is movably positioned within the housing. An eccentric disk is fixed to the drive spindle and a ring is rotatably mounted on the disk and has teeth on its circumferential periphery. An arcuate portion of the teeth on the ring intermesh with teeth formed in the housing. Due to the eccentricity of the disk and ring, during each 360* turn of the drive spindle there is a displacement of the ring relative to the housing. Abutment surfaces are provided on the ring extending toward the slide. The slide is displaceable between two positions and has a pair of abutments so that in each of its positions one of its abutments is located in the path of the abutment surfaces on the ring. When the abutment surface on the ring contacts the abutment on the slide further angular movement of the drive spindle in a particular direction is prevented.

ilnited States Kouth et al.

atent 1 DEVICE FOR LIMITING ROTATION [75] Inventors: Herbert Kouth,

Schoneck-Kilianstadten; Fritz Marr, Offenbach/Main; Rudolf Roos,Bischofsheim/Hanau, all of Germany [73] Assignee: H. T. Golde GmbI-l,Frankfurt/Main,

Germany [221 Filed: July 14, 1972 [21] Appl. No.: 272,068

[30] Foreign Application Priority Data July 15, 1971 Germany P 21 35359.2

[52] US. Cl 74/l0.2, 296/137 G, 296/137 H [51] Int. Cl. Fl6h 35/18 [58]Field of Search 74/526, 10.2; 296/137 G, 137 E, 137 H [56] ReferencesCited UNITED STATES PATENTS 2,991,662 7/1961 Werner 74/10.2 X 3,411,36611/1968 Leto 74/l0.2

Primary Examiner-Milton Kauffman Assistant Examiner-Frank l-l. McKenzie,Jr. Attorney-David Toren et a1.

[57] ABSTRACT For limiting the rotational or angular movement of a drivespindle about its axis, such as in a rotary drive for the sliding roofof a motor vehicle, abutments or stops are associated with the drivingspindle and with a slide movably displaceable relative to andtransversely of the drive spindle, for effecting the limiting action.The drive spindle extends through a housing and the slide is movablypositioned within the housing. An eccentric disk is fixed to the drivespindle and a ring is rotatably mounted on the disk and has teeth on itscircumferential periphery. An arcuate portion of the teeth on the ringintermesh with teeth formed in the housing. Due to the eccentricity ofthe disk and ring, during each 360 turn of the drive spindle there is adisplacement of the ring relative to the housing. Abutment surfaces areprovided on the ring extending toward the slide. The slide isdisplaceable between two positions and has a pair of abutments so thatin each of its positionsone of its abutments is located in the path ofthe abutment surfaces on the ring. When the abutment surface on the ringcontacts the abutment on the slide further angular movement of the drivespindle in a particular direction is prevented.

10 Claims, 4 Drawing Figures PATENTEU BET 91975 sum 2 0r 3 DEVICE FORLIMITING ROTATION SUMMARY OF THE INVENTION The present invention isdirected to a device for limiting the number of turns or revolutions ofa rotary member, such as the driving spindle in a rotary drive for thesliding roof of a motor vehicle, and, more particularly, it is concernedwith the arrangement of a slide for selectively positioning abutmentmeans within a housing.

In a device of the kind to which the present invention is directed, adisk is rigidly secured on and extends transversely of a drive spindleand the axis of the disk is offset or eccentric to the axis of thespindle. A ring is rotatably mounted on the circumferential periphery ofthe disk and the outer circumferential periphery of the ring is providedwith gear teeth. The device includes a housing disposed laterally abouta part of the drive spindle and providing a cylindrically-shaped surfacelaterally enclosing the ring. The cylindrically shaped surface isconcentric to the axis of the drive spindle and, as a result, is offsetrelative to the circumferential periphery of the ring. Gear teeth areformed in the cylindrically shaped surface and the radius of thededendum circle of the gear teeth on the cylindrically shaped surface islarger than the radius of the addendum circle of the gear teeth on thering by an amount which corresponds to the eccentricity of the diskrelative to the axis of the drive spindle. As a result, only a portionof the teeth on the periphery of the ring are in intermeshing engagementwith the teeth on the cylindrically shaped surface of the housing.During each complete turn of the drive spindle, the ring moves a certaindistance relative to the housing. The ring and the housing each havecooperating abutment or stop means for halting the angular movement ofthe drive spindle after a predetermined number of turns or revolutionshave been made.

A device of this type is disclosed in U.S. Pat. No. 2,991,662, issuedJuly 11, 1961, and has proven to be especially suitable as the drive forsliding roofs in motor vehicles. The characteristic of the device whichmakes its use desirable, is that a reliable limitation on the number ofturns of a drive spindle can be achieved at insignificant cost and theparts required can be accommodated, without any additional spacerequirements, in the body or housing which customarily encloses aportion of the drive spindle. As is known from the prior art device, thelimitation on the number of revolutions of the drive spindle serves tolimit the path through which a sliding roof travels while avoiding anyoverloading of the transmission or gearing when the end position of thesliding roof has been reached. Further, by means of this device, it ispossible to prevent the rigid sliding roof, and particularly its rearedge, from striking the roof frame with excessive force at the end ofits travel. a

In U.S. Pat. No. 3,507,537, issued Apr. 21, 1970, another sliding roofconstruction is disclosed in which the sliding roof or cover can beselectively raised in the manner of a inwardly hinged venting flap bylifting the rear edge of the cover or by displacing it out of the roofopening into a receiving space below the roof. In this more recentsliding roof construction, it is desirable to construct the drive sothat it can perform both the raising function and the sliding function.To perform both functions, a single actuating element is used, such as ahandcrank, if a manually operated drive is to be employed. Therefore, itis the primary object of the present invention to provide a simplyconstructed device for limiting both the sliding movement and theraising movement of a sliding roof. In other words, it is the purpose ofthe present invention to provide a device which limits the number ofturns of a drive spindle used for effecting two different courses ofmovement.

In accordance with tht present invention, abutment or stop members forthe housing are positioned on a slide which is displaceably mounted inthe housing for movement in a direction transverse of the drive spindle.By locating the slide between two positions, it is possible to locatedifferent ones of the abutment members in the path of the abutment meanslocated on the ring. In this manner, the limitation caused by theengagement of the abutment means can be released so that the drivingmovement can be continued in the same rotational direction. In this wayand in a very simple manner, the number of turns can be multiplied orrepeated in a stepwise manner or can be reduced in a stepwise manneruntil the desired limit on the movement has been reached. Moreover, ifthe slide is angularly adjustable about the axis of the driving spindle,the limiting action can be provided without any stepwise action or invariable steps or progressions. 7

However, the preferred embodiment of the present invention, that is forlimiting the number of turns or revolutions of the drive spindle for thedrive of a sliding roof, operates only with a linearly adjustable slide.

If the device is used in carrying out the two different movements of asliding roof construction, preferably, a pair of abutment members areprovided on the slide each disposed on an opposite side of the axis ofthe drive spindle so that one of the abutment members is always situatedin the path of movement of the abutment means on the ring. Further, theslide is provided with an oblong hole or slot for permitting thtdisplacement of the slide relative to the drive spindle which extendsthrough the slide. Accordingly, it is possible to limit the number ofturns of the drive spindle for each of the different movements effectedby the sliding roof. Additionally, if two angularly spaced abutmentsurfaces are provided on the ring, as is preferred in accordance withthe invention, then a limitation of the number of turns can be affordedin both of the rotational directions of the spindle. By the selectiveconstruction and arrangement of the abutment means on the ring and/orthe housing, a number of different stop positions can be provided forthe drive spindle.

In a sliding roof construction, such as disclosed in U.S. Pat. No.3,507,537, it is sufficient if only two stop arrangements are providedfor the drive spindle, that is one for the end of the closing movementof the sliding roof and the other for the end of the tilting movement ofthe sliding roof, while the limitation on the opening displacement canbe provided by the engagement of the cover with the frame of the roofand, with regard to the raising movement, by the lifting means employed,for example, the lifting linkage. To prevent any problems bydisplacement of the slide prior to the engagement of the differentabutments, the slide, in a particularly advantageous embodiment of theinvention, is blocked from displacement because the abutment surfaceson' the ring are provided by the two end surfaces of an arcuatelyextending blocking rib which is concentrically mounted on the ring andextends for an angular portion of the ring. The blocking rib preventsany premature engagement with the inactive abutment member on the slide.

To assure that the slide is always maintained in one of its twopositions, a spring is positioned in the housing and contacts the slidefor holding it in either of the positions in which it is located. Toprovide the necessary locking or holding action between the slide andthe spring, the slide is provided with a V-shaped cam extendingoutwardly from one of the sides of the slide which extends in thedirection of its movement. Within a recess in the housing located on thesame side of the slide as the cam, a stirrup spring is positioned with aprojection shaped in the same manner as the cam for engagement with thecam so that the slide is held or biased in whichever position it islocated. With the apex of the projection on the stirrup spring directedtoward the apex of the cam on the slide and with the projection on thespring located in the middle of the path of movement of the slide, ifthe slide is not fully displaced into either of its two positions, thespring will bias the slide into one of its end positions so that onlyone course of movement of the sliding cover can be effected.

For displacing the slide between its two positions, a recess is providedin one of the sides which extends in its direction of movement. Todisplace the slide, a lever is pivotally mounted on the housing with oneend extending into the recess on the slide and the other projectingoutwardly from the housing. Preferably, a hatshaped actuating button ispositioned on the end of the lever located outwardly of the housing andthe button is arranged so that in each of the positions of the slide itis in surface contact with the housing.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there is illustrated and described a preferredembodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a vertical sectional view through a device embodying thepresent invention;

FIG. 2 is a view taken along line 11-" in FIG. 1;

FIG. 3 is a view taken along line III-III in FIG. 1; and

FIG. 4 is a view taken along line IVIV in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1 a drive spindle l isshown extending through a housing 6 with one end 2 of the spindleserrated for receiving a handcrank, not shown, for manually turning thespindle. Secured to the opposite end of the spindle is a driving pinion3. In a known manner, the driving pinion 3 is engaged on two oppositesides with a pair of movably guided threaded cables, not shown, foractuating a sliding roof cover. Bores 5 extend through the housing formounting the device on a sheet metal part of a vehicle body. Furtherillustration and description of the cable drive for sliding grooves isconsidered unnecessary, since such a drive is well known and, inaddition, the present invention does not relate to such a cable drive.The housing 6 includes a cover 8 having a recess 7 through which thedriving spindle 1 extends. The drive spindle 1 is rotatably mountedwithin the housing with the portion 9 adjacent the drive pinion 3mounted in a bearing cover 11 fitted within the housing 6 and withanother portion 10 supported in a bearing ring 12. The bearing ring 12is seated within the housing.

The housing 6 and its cover 8 are formed of a diecast metal and arerigidly connected together by means of bushings 13 formed integral withthe cover and extending through the bores 5 in the housing. The innersurfaces of the bushings define the surfaces of the bores 5. The ends ofthe bushings spaced from the cover are deformed into engagement with thehousing. Bearing cover 11 is fitted into the surface of the housingopposite the cover 8 and is secured, such as by caulking. On the end ofthe drive spindle 1 adjacent the driving pinion 3, a disk 14 isconnected in a groove on the shaft and fixes the axial position of thepinion. On the spindle 1 between portions 9 and 10, an eccentric disk 15is rigidly connected to the spindle and, preferably, is formedintegrally with the spindle. In FIG. 3, the eccentricity e between theaxis of the disk and the axis of the spindle 1 is indicated. Rotatablymounted on the circumferential periphery of the disk 15 is a ring 17which has gear teeth 16 extending about its outer circumferentialperiphery. Within its interior, the housing 6 has a cylindrically shapedsurface 19 laterally enclosing the ring 17. Gear teeth 18 are formed inthe cylindrically shaped surface 19 and, as shown in FIG. 3, a portionof the gear teeth 16 and 18 are in intermeshed engagement. The radius ofthe dedendum circle of the gear teeth 18 on the cylindrical surface 19is larger than the radius of the addendum circle of the gear teeth 16 onthe ring 17 by an amount which corresponds substantially to the extentof the eccentricity of the disk 15 to the axis of the drive spindle 1.Accordingly, in the embodiment shown in the figures, there are 35 gearteeth 16 on the ring and 36 gear teeth 18 on the cylindrically shapedsurface 19, that is there is one more gear tooth 18 than gear teeth 16.

The device, as described thus far, operates in the following manner: asthe drive spindle and the other parts rigidly secured to it are rotatedin one or the other direction about the axis of the spindle, the ring,rotatably mounted on the eccentric disk 15 with a portion of its gearteeth 16 in contact with the stationary counter gear teeth 18 moveswithin the housing 6. Since the number of teeth between the two sets ofgear teeth differ by one tooth, the relative position between the ring17 and the cylindrically shaped surface 19, after one revolution of thedrive spindle 1, is displaced, by an amount equal to one tooth spacing,in the circumferential direction. The ring 17 turns in the directionopposite to the rotation of the drive spindle, however, at a lesserangular speed. Accordingly, after a number of complete turns of thedrive spindle, which number can be exactly determined and calculated,the arrangement of abutments or stops on the ring and correspondingstationary abutment members within the housing result in a blockage ofthe spindle so that no further turning action in a particular directioncan be effected. When the spindle 1 is prevented from turning, thedriving pinion 3 can no longer transmit movement to the parts associatedwith it and the movement of such parts is discontinued.

As can be seen in FIGS. 1 and 2, a flat slide 21 is positioned within arecess 22 formed in the housing 6 with the recess and the slide havingcorresponding rectangular shapes so that the recess 22 limits thedisplacement or path of movement of the slide 21 relative to thestationary housing 6. The slide 21 has a pair of abutment membersextending from the slide in the direction of the ring 17. Slots 23 areprovided in the housing for affording the movement of the abutmentmembers 20. Within the housing 6, spaced axially from the cylindricallyshaped surface 19 and concentric with the axis of the spindle 1, is anannular channel 24. The slots 23 through the housing open into theannular channel 24 so that the abutment members 20 can be positionedwithin the channel. The channel 24 forms a path of movement for theabutment means associated with the ring 17.

As shown best in FIG. 3, the abutment means associated with the ring 17are provided by the two end faces 25, 26 of the arcuately shapedblocking rib 27 which is secured on the face of the ring directed towardthe cover 8. The rib 27 projects from the ring into the annular channel24 and passes through the channel as the ring moves relative to thehousing. In limiting or block ing the rotation of the driving spindle 1,the abutment surface cooperates with the surface 28 on one of theabutment members 20 of the slide, while the abutment surface 26 isassociated with the surface 20 on the other abutment member 20.Accordingly, displacement of the slide within the housing is possibleonly if the surfaces 25, 28 (as shown) or the surfaces 26, 29 are inengagement with one another. In any other position of the ring 17relative to the housing 6, the rib 27 provides a blockage across theslots 23 preventing the movement of the abutment members 20 into and outof the respective portions of the annular channel 24. As viewed in thevertical position in FIG. 2, the slide 21 can be moved downwardly withinthe recess 22 relative to the housing 6 so that the rotational directionof the ring 7 previously blocked by the engagement of the sur faces 25,28 is again clear corresponding to the opposing rotational direction ofthe spindle 1. If the device is to be used as described above, thenecessity for releasing the blockage occurs when the roof cover has beenpushed into its closed position and, subsequently, with the same crankdirection, is to be raised or lifted, or when the lifted or raised coverduring the folding down movement, in which the crank is turned in theopposing direction, has reached its end position and, subsequently, withthe same crank direction the cover is pushed under the stationary roofpart for opening the roof. The slide 21 has an elongated slot 30 throughwhich the drive spindle extends for permitting the movement of the sliderelative to the spindle. One of the sides of the slide, extending in thedirection of its movement, has an outwardly projecting cam 31 whichcooperates with a stirrup spring 33 engaged within a re cess portion 32in the housing 6, the recess portion forms an extension of the recess22. Due to the cooperation between the slide 21 and the stirrup spring33, it is only possible for the slide to assume one of two positions,that is the position as shown in FIG. 2 with the slide in contact withthe upper end of the recess 22 or the position shown in dot-dash linesin FIG. 2 with the slide in contact with the lower end of the recess 22.Accordingly, it is not possible for the slide to assume an intermediateposition where the blocking action of the surfaces 25, 28 or 26, 29would not be effective. The cam 31 has a V-shaped configuration with itsapex spaced outwardly from the side of the slide 21. Similarly, thestirrup spring, intermediate its ends, has a V- shaped projectionextending toward the slide and corresponding in configuration to theV-shaped cam. In the position shown in FIG. 2, the projection of thespring 33 holds or biases the slide in its upper position. If the slideis pushed downwardly until the apex of the cam 31 passes the apex formedby the projection of the spring 33, the action of the spring will biasthe slide in the downward direction and will hold it in that positionagainst displacement. Therefore, it can be readily appreciated that theslide can be positioned in only two different positions.

On the opposite side of the slide 21 from the cam 31, a recess 34 isprovided into which one end of an actuating lever 36 is engaged. Thelever 36 is pivotally mounted on the housing 6 by means of a pin 35which is located intermediate the ends of the lever. The lever 36extends outwardly through a slot 37 formed in the housing 6 so that itsend opposite the end located in the recess 34 extends outwardly from thehousing 6. Articulated to the outwardly projecting end of the lever 36is a hat-shaped actuating button 33 having a surface generallyconforming to the surface along the periphery of the housing. In FIG. 2,the button 38 is shown in full lines when the slide is in the upperposition and is shown in dot-dash lines when the slide has been moved toits lower position. In these two positions of the button 38, it is insurface contact with the periphery of the housing 6.

What is claimed is:

1. A device including a drive spindle and the device arranged forlimiting the revolution of said drive spindle such as for use in therotary drive for the sliding roof of a motor vehicle, a disk rigidlyconnected to and extending transversely of said drive spindle, the axisof said disk being disposed eccentrically of the axis of said drivespindle, a ring rotatably mounted on the circumferential periphery ofsaid disk and having gear teeth formed in its outer circumferentialperipheral surface, a stationary housing laterally enclosing said diskand ring and having a cylindrically shaped surface concentric with theaxis of said shaft and disposed about the circumferential periphery ofsaid ring, said housing having gear teeth formed in said cylindricallyshaped surface, the radius of the dedendum circle of said teeth on saidhousing being larger than the radius of the addendum circle of saidteeth on said ring by an amount substantially equal to the eccentricityof said disk relative to the axis of said drive spindle, abutment meanson said housing and said ring for limiting the angular movement of saiddrive spindle, wherein the improvement comprises a slide mounted in saidhousing and extending transversely of the axis of said drive spindle,said abutment means comprises a pair of spaced abutment members securedto and extending outwardly from said slide toward said ring, said slidebeing movably positionable within said housing transversely of the axisof said drive spindle for selectively alternatively locating one of saidabutment members in the path of said abutment means on said ring withthe other said abutment member disposed out of the path of said abutmentmeans on said ring for providing a stop for the angular movement of saiddrive spindle.

2. A device, as set forth in claim 1, wherein said abutment members onsaid slide being located on opposite sides of the axis of said drivespindle relative to one another and said slide and abutment membersbeing arranged so that one of said abutment members is always in thepath of movement of said abutment means on said ring.

3. A device, as set forth in claim 2, wherein said slide has a slottherethrough elongated in the direction of movement of said sliderelative to said drive spindle- ,and said drive spindle extends throughsaid slot.

4. A device, as set forth in claim 1, wherein said abutment means onsaid ring comprises a pair of angularly spaced abutment surfaces securedto and extending from said ring toward said slide.

5. A device, as set forth in claim 4, wherein said abutment meanscomprises a rib secured to and extending outwardly from the face of saidring directed toward said sleeve, said rib having an arcuateconfiguration being spaced inwardly of the circumferential periphery ofsaid ring and being disposed concentrically of the axis of said ring,and said pair of abutment surfaces each located on an opposite end ofsaid rib.

6. A device, as set forth in claim 1, wherein said slide beingpositionable between a first position and a second position, and springmeans associated with said housing for holding said slide in the one ofthe first and second positions into which it is located and for biasingsaid slide from any intermediate position into one of the first andsecond positions.

7. A device, as set forth in claim 6, wherein said housing having arecess therein extending along one side of the path of movement of saidslide, said slide having a V-shaped cam projecting outwardly from theside thereof adjacent said recess into the recess in said housing, andsaid spring means comprising a stirrup spring positioned within saidrecess and having a V-shaped projection extending into the path of saidcam for engaging said cam in each of the first and second positions ofsaid slide for holding said slide in the one of the first and secondpositions in which it is located.

8. A device, as set forth in claim 1, wherein said slide beingpositionable between a first position and a second position, said slidehaving a notch formed in one of the sides thereof extending in thedirection of movement of said slide relative to said drive spindle, andmeans articulated to said housing and positioned within said notch formoving said slide between the first and second positions thereof.

9. A device, as set forth in claim 8, wherein said means for moving saidslide comprises a lever pivoted to said housing and extending at one endinto said notch in said slide and having its other end projectingoutwardly from said housing so that said outwardly extending end can bemanipulated for actuating said lever and displacing said slide betweenits first and second positions.

10. A device, as set forth in claim 9, wherein a hatshaped actuatingbutton articulated to the outer end of said lever and disposed insurface contact with the periphery of said housing in each of the firstand second positions of said slide.

1. A device including a drive spindle and the device arranged forlimiting the revolution of said drive spindle such as for use in therotary drive for the sliding roof of a motor vehicle, a disk rigidlyconnected to and extending transversely of said drive spindle, the axisof said disk being disposed eccentrically of the axis of said drivespindle, a ring rotatably mounted on the circumferential periphery ofsaid disk and having gear teeth formed in its outer circumferentialperipheral surface, a stationary housing laterally enclosing said diskand ring and having a cylindrically shaped surface concentric with theaxis of said shaft and disposed about the circumferential periphery ofsaid ring, said housing having gear teeth formed in said cylindricallyshaped surface, the radius of the dedendum circle of said teeth on saidhousing being larger than the radius of the addendum circle of saidteeth on said ring by an amount substantially equal to the eccentricityof said disk relative to the axis of said drive spindle, abutment meanson said housing and said ring for limiting the angular movement of saiddrive spindle, wherein the improvement comprises a slide mounted in saidhousing and extending transversely of the axis of said drive spindle,said abutment means comprises a pair of spaced abutment members securedto and extending outwardly from said slide toward said ring, said slidebeing movably positionable within said housing transversely of the axisof said drive spindle for selectively alternatively locating one of saidabutment members in the path of said abutment means on said ring withthe other said abutment member disposed out of the path of said abutmentmeans on said ring for providing a stop for the angular movement of saiddrive spindle.
 2. A device, as set forth in claim 1, wherein saidabutment members on said slide being located on opposite sides of theaxis of said drive spindle relative to one another and said slide andabutment members being arranged so that one of said abutment members isalways in the path of movement of said abutment means on said ring.
 3. Adevice, as set forth in claim 2, wherein said slide has a slottherethrough elongated in the direction of movement of said sliderelative to said drive spindle,and said drive spindle extends throughsaid slot.
 4. A device, as set forth in claim 1, wherein said abutmentmeans on said ring comprises a pair of angularly spaced abutmentsurfaces secured to and extending from said ring toward said slide.
 5. Adevice, as set forth in claim 4, wherein said abutment means comprises arib secured to and extending outwardly from the face of said ringdirected toward said sleeve, said rib having an arcuate configurationbeing spaced inwardly of the circumferential periphery of said ring andbeing disposed concentrically of the axis of said ring, and said pair ofabutment surFaces each located on an opposite end of said rib.
 6. Adevice, as set forth in claim 1, wherein said slide being positionablebetween a first position and a second position, and spring meansassociated with said housing for holding said slide in the one of thefirst and second positions into which it is located and for biasing saidslide from any intermediate position into one of the first and secondpositions.
 7. A device, as set forth in claim 6, wherein said housinghaving a recess therein extending along one side of the path of movementof said slide, said slide having a V-shaped cam projecting outwardlyfrom the side thereof adjacent said recess into the recess in saidhousing, and said spring means comprising a stirrup spring positionedwithin said recess and having a V-shaped projection extending into thepath of said cam for engaging said cam in each of the first and secondpositions of said slide for holding said slide in the one of the firstand second positions in which it is located.
 8. A device, as set forthin claim 1, wherein said slide being positionable between a firstposition and a second position, said slide having a notch formed in oneof the sides thereof extending in the direction of movement of saidslide relative to said drive spindle, and means articulated to saidhousing and positioned within said notch for moving said slide betweenthe first and second positions thereof.
 9. A device, as set forth inclaim 8, wherein said means for moving said slide comprises a leverpivoted to said housing and extending at one end into said notch in saidslide and having its other end projecting outwardly from said housing sothat said outwardly extending end can be manipulated for actuating saidlever and displacing said slide between its first and second positions.10. A device, as set forth in claim 9, wherein a hat-shaped actuatingbutton articulated to the outer end of said lever and disposed insurface contact with the periphery of said housing in each of the firstand second positions of said slide.